Sample handling system for auto exhaust analyzer



SAMPLE HANDLING SYSTEM FOR AUTO EXHAUST ANALYZER Filed Nov. 8, 1967 SUPPLY PRESSURE REDREG. 1 2 l 11 Is x I I4 [5' AUTO 1- ETECTO Q EXHAUT Y a /24 U V A ER 23 VACU M B RRI I INVENTOR, LARRY D. GAMACHE BYTZ MAW AT TORNEY United States Patent Olfice 3,537,296 Patented Nov. 3, 1970 3,537,296 SAMPLE HANDLING SYSTEM FOR AUTO EXHAUST ANALYZER Larry D. Gamache, Yorba Linda, Calif., assignor to Beckman Instruments, Inc., a corporation of California Filed Nov. 8, 1967, Ser. No. 681,483 Int. Cl. G01n 1/24, 33/00 US. CI. 73-23 2 Claims ABSTRACT OF THE DISCLOSURE A sample handling system for an auto exhaust analyzer to provide pressure boosting to cause the auto exhaust to flow through a hydrogen flame detector at temperatures above 150 C. without overheating the pump by providing a sample pump subsequent to the detector. A bypass around the detector increases flow rate and response. A vacuum barrier is also shown surrounding the detector to shield it from atmospheric contamination. An auxiliary air supply is connected to a point between the detector and the pump to keep the flow through the pump at the desired temperature and pressure.

BACKGROUND OF THE INVENTION SUMMARY OF THE INVENTION Accordingly, it is an object of this invention to provide a sample handling system for auto exhaust analyzers which will reduce the temperature of the pump and maintain the pressure going into the pump at a constant level.

Another object of the invention is to provide a vacuum barrier around the detector to prevent atmospheric contamination from afi'ecting the output of the detector.

These and other objects are achieved by providing a sample handling system for an auto exhaust analyzer including an analyzer through which the exhaust is drawn by means of a sample pump. An auxiliary air supply is drawn through a pressure reduction regulator to the point in the stream between the analyzer and the pump to maintain the pressure at that point constant and reduce the pump temperature.

In another aspect of the invention, a vacuum barrier may be provided around the detector within the oven.

The novel features which are believed to be characteristic of the invention are set forth with particularity in the appended claims. The invention and further objects and advantages thereof can best be understood by reference to the following description and accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING The drawing is a partially schematic flow diagram of the exhaust sample handling system of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Turning now to the drawing, an analyzer 10 is illustrated including a hydrogen flame detector 11 enclosed in a vacuum barrier 12 which is enclosed in turn in an oven 13 for regulating the detector temperature. The auto exhaust enters through the line 14 and passes through the detector 11 the line 15, a flow restrictor 16 and pump 17 to a vent 18 where it is vented to air. That portion of the line 14 external to the oven 13 may be heated to prevent the exhaust from cooling and undergoing a change in composition. A supplementary air supply is connected through a line 19 and a pressure reduction regulator 20 to a connection 21 with line 15 at which point it is desired to maintain constant pressure. A pressure indicator 22 indicates the pressure at this point. A supplementary line 23 is connected from the vacuum barrier 12 to the line :15 in order that the pump 17 can serve to evacuate the barrier 12 to isolate the detector 11 from atmospheric contamination by eliminating a pressure differential between the detector and the inside of the barrier which would have caused flow of atmospheric contamination to leak through the vacuum barrier into the detector.

A bypass line 24 is connected in parallel with the detector 11 and contains a restrictor 25. The purpose of this bypass line 24 is to increase the flow rate of the auto exhaust in order to speed up the detector response.

Specific components employed in implementing one embodiment of the invention were a Beckman Model 173,145 hydrogen flame detector for the detector 11, a inch needle valve for the flow restrictor 16, a Model 1531-V-107-288 carbon vane pump for the pump 17 manufactured by Gast Manufacturing Corporation, Benton Harbor, Mich., and a Model 43-20 pressure reduction regulator for the regulator 20 manufactured by Moore Products Company of Philadelphia, Pa.

The auto exhaust enters the line 14 at above C. The normal flow rate through the detector 11 varied from 0 to 50 c.c. per minute. The bypass 24 flow rate varies from 1 to 5 liters per minute. The sample sump 17 has a 20 liter per minute maximum rate. Constant flow conditions are maintained through the detector 11 by the pressure reducing regulator 20 which serves to hold a constant pressure at the point 21 satisfying that portion of the rate requirement of the pump 17 not provided through detector 11 and bypass 24 and simultaneously serving to reduce the temperature of the air flowing through pump 17.

Since the principles of the invention have now been made clear, modifications which are particularly adpated for specific situations Without departing from those principles will be apparent to those skilled in the art. The appended claims are intended to cover such modifications as well as the subject matter described and to only be limited by the true spirit of the invention.

What is claimed is:

1. An auto exhaust analyzer sample handling system including an analyzer,

- draw sample having a high temperature therethrough,

a pressure reduction regulator, means for conveying an auxiliary air supply through said pressure reduction regulator to a point between 5 said analyzer and said pump means to maintain the pressure at said point constant and to reduce the pump temperature by providing a substantial portion of the total flow therethrough and a restrictor connected between said point and said pump.

2. The system of claim 1 wherein said analyzer includes a detector and a bypass is connected in parallel with said detector to increase the speed of detector response.

' References Cited UNITED 'STA TES PATENTS Y 2,506,535 5/1950 Zaikowsky 7327 3,391,570 7/1968 Becker 7323 RICHARD C. QUEISSER, Primary Examiner C. E. SNEE IH, Assistant Examiner US. 01. X.R. 73-4215 

